How to get the Widget Editor in WordPress larger, too narrow

How to get the Widget Editor in WordPress larger, too narrow. The UI under Appearance> widgets is wider, but not enough, to work with you GRID in Footer.

ANTWORT:

The UI is controlled by WordPress, the theme can not change its width,
unfortunately!.
I wrote the below PHP code to insert CSS to the admin area, can you give it a
try?

Adding PHP: https://docs.generatepress.com/article/adding-php/

wp_add_inline_style( 'wp-block-library', 
'.blocks-widgets-container .editor-styles-wrapper, .wp-block[data-type="core/widget-area"] {
max-width:100%;
}' 
);